I. Field
The present invention relates generally to communication, and more specifically to techniques for parsing (or demultiplexing) data into multiple streams in a communication system.
II. Background
A multiple-input multiple-output (MIMO) communication system employs multiple (T) transmit antennas at a transmitting entity and multiple (R) receive antennas at a receiving entity for data transmission. A MIMO channel formed by the T transmit antennas and the R receive antennas may be decomposed into S spatial channels, where S≦min {T, R}. The S spatial channels may be used to transmit data in a manner to achieve higher overall throughput and/or greater reliability.
The S spatial channels may experience different channel conditions (e.g., different fading, multipath, and interference effects) and may achieve different signal-to-noise-and-interference ratios (SNRs). The SNR of each spatial channel determines its transmission capability, which is typically quantified by a particular data rate that may be reliably transmitted on the spatial channel. If the SNR varies from spatial channel to spatial channel, then the supported data rate also varies from channel to channel. Furthermore, if the channel conditions vary with time, then the data rates supported by the spatial channels also vary with time.
A major challenge in a coded MIMO system is parsing data into multiple streams in a manner such that good performance can be achieved for all streams. This parsing is complicated if different data rates can be used for different streams and these streams can carry different numbers of bits in a given time interval. The parsing is further complicated if different data rates are associated with different puncture patterns, as described below.
There is therefore a need in the art for techniques to parse data into multiple streams with different data rates.